<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>老色批</title>
    <style> div {
        /*显示边框*/
        border: 1px solid blueviolet;
        /*宽度*/
        width: 60%;
        /*高度*/
        height: 500px;
        /*外边距*/
        margin: auto;
    }</style>

</head>
<body>
<div> 一开口</div>
<div> 一开口</div>
</body>
</html>